Method and system for residence time measurement of simulated food particles in continuous thermal food processing and simulated particles for use in same

ABSTRACT

A method of generating a residence time measurement of a particulate-containing food product while passing the product as a continuous stream through a thermal processing apparatus is described. The method includes the steps of inserting at least one detectable particle, and preferably many detectable particles, tagged with at least one magnetic implant into the stream at pre-selected intervals; detecting the at least one implant using at least one sensor located at a detection point downstream from a location of the inserting of the at least one detectable particle; determining a time of passage of the at least one detectable particle in the stream using output from the at least one sensor; and generating a residence time measurement for the stream using the time of passage for the at least one detectable particle. The method also includes the use of multiple sensors for detecting the implants. A suitable system and detectable particle for carrying the method are also described.

TECHNICAL FIELD

[0001] The present invention relates generally to continuous thermalprocessing of a particulate-containing food product, and more particularto a method and system for generating residence time measurements forsuch processes, and a detectable particle for use in such a method andsystem.

BACKGROUND ART

[0002] It will be appreciated by those having ordinary skill in the artthat thermal processing of particulate-containing food products isdifficult to accomplish in an efficient but effective manner.Particulate-containing food products are also described in the art asmulti-phase food products, or as multi-phase foods, in that theseproducts include liquids and solids.

[0003] Traditionally, thermal processing of particulate-containing foodproducts involved the placing of the product in individual cans,followed by thermal treatment of the product within the can. The processis generally effective in removing microbial contamination and inproviding a food product that is safe for consumption. However, thisprocess is labor and machinery-intensive and time-consuming. Thus, thisprocess lacks efficiency.

[0004] Continuous thermal processing generally involves the thermalprocessing of the food product as a stream or flow in one line whileprocessing the containers or cans in which the food will be stored inanother line. The food product is then placed in the container underappropriate conditions wherein microbes and their spores are excluded.Continuous thermal processing thus enables unlimited package size,yielding increased efficiencies and reduced costs to the industry andultimately to the consumer. Continuous thermal processing is sometimesalso called aseptic processing in the art.

[0005] However, it is very difficult to uniformly treat all fluidelements of the food product flowing in a continuous process. Thisdifficulty is exacerbated in the case of a multi-phase food product inthat there are variations in speed for each solid food particle flowingthrough the process. Thus, the residence time of each food particle inthe flow is a difficult variable to characterize.

[0006] As is known in the art, the residence time for a particle in amulti-phase food product traveling through a continuous thermalprocessing line is that amount of time that the particle resides in agiven length or section of the line, or in the entire line itself.Residence time is an important variable because, among other things, itis necessary to the calculation of the lethality per particle for thecontinuous thermal process. As is also known in the art, lethality canbe calculated as a function of time using several equations that requiretemperature and residence time measurements, among other measurements.Stated differently, lethality is that amount of time a particle issubjected to a temperature sufficient to kill a microbe common to foodparticles and its spores. An example of such a microbe is Clostridiumbotulinum.

[0007] It is particularly important to capture the residence timemeasurement for the fastest particle traveling through the process. Forthe fastest particle, the risk of insufficient lethality is great.Optionally, the food stream can be subjected to excessive heat in thethermal process, but this results in food product that is, in effect,overcooked and therefore not palatable to the consumer. This option isnot viable in a commercial setting.

[0008] The problems of continuous thermal processing of multi-phase foodproducts are more fully discussed in Tucker, C. S. and Withers, P. M.,“Determination of Residence Time Distribution of Food Particles inViscous Food Carrier Fluids using Hall effect sensors”, TechnicalMemorandum 667, Campden Food and Drink Research Association (CFDRA),Campden, Glos., U.K. (1992) and in “Case Study for Condensed Cream ofPotato Soup”, Aseptic Processing of Multi-phase Foods Workshop, Nov.14-15, 1995 and Mar. 12-13, 1996 (published 1997).

[0009] Because of the above referenced difficulties, in the UnitedStates each continuous thermal process for use in the treatment of foodmust be described in a document to be filed with the United States Foodand Drug Administration (FDA) for approval before it can be implementedin industry. Because of the problems associated with uniform treatmentin the continuous thermal process, the FDA subjects these documents,hereinafter referred to as “FDA process filings”, “process filings” or“FDA filings”, to rigorous scrutiny.

[0010] To gain FDA approval, a process filing must demonstratebiovalidation of the process, among other information. As in known inthe art, biovalidation refers to data showing that the process waseffective in removing contamination of the food product by microbes andtheir spores. To determine biovalidation, conservative residence timedistribution measurements are required. Lengthy test runs must beperformed to generate the conservative residence time distributionmeasurements. Such test runs require a great deal of time and involvethe loss of a great deal of the food product, as the food product thatis part of the test run cannot be salvaged. The time required for andfood product lost in such test runs have prevented the wide scaleadoption in the industry of continuous thermal processing ofparticulate-containing food products.

[0011] There have been several attempts to provide methods and systemsfor characterizing residence time in continuous thermal processing ofparticulate-containing food products that reduce the time and amount offood product required to validate the process. Currently availablemethods and systems use the detection of a detectable particle. By theterm “detectable particle” it is meant a particle that includes a tracercomponent that is detectable by sensors used in the method and systemand that is attached to or integrated into a carrier component or mediumof the particle. The particle is then introduced into the food stream ofthe continuous thermal process for detection.

[0012] Examples of the tracer element include magnetic tracer materialswhich comprise magnetic particles and metal powders. The particles orpowders are mixed in a matrix of solidified plastic polymer or into a analternative medium such as an alginate gel.

[0013] These magnetic tracer materials are only partially compatiblewith their intended use for measurements of residence time of foodparticles. Their high density causes an increase in the density ofloaded particles which leads to an underestimate of particle velocity.This can lead to an overestimate of hold times and thus yield acalculated process of insufficient lethality to microorganisms and theirspores in the food product being processed.

[0014] For example, Segner et al., “Biological Evaluation of a HeatTransfer Simulation for Sterilizing Low-Acid Large Particulate Foods forThermal Packaging”, Journal of Food Processing and Preservation,13:257-274, (1989), reported the use of magnetic implants to tag foodparticles and measure residence times in thermal systems. Wound coppercoils were used as sensor elements, and a single type of magneticimplant was used in the detectable particles. No density compensationfor the detectable particles was implemented. The problems with the useof wire coils as magnetic sensors include low sensitivity and lowdetection reliability at low particle velocities since magnetic flux isdetected rather than magnetic field. This approach was followed in “CaseStudy for Condensed Cream of Potato Soup”, Aseptic Processing ofMulti-phase Foods Workshop, Nov. 14-15, 1995 and Mar. 12-13, 1996(published 1997), referenced above.

[0015] Tucker, G. S. and Richardson, P. S., “Residence Time Distributionand Flow Behavior of Foods Containing Particles in Thermal Processing”,AIChem.E Conference on Food Engineering, Chicago (Feb. 21-24, 1993)(Poster Paper) describes the use of multiple Hall effect sensors mountedaround line tubes at different locations to detect the time of passageof magnetically tagged particles through the tube during continuous flowthermal processing. No density compensation of particles was used, and asingle particle tag type was applied in detection. Hall effect sensorsare more sensitive than wound coil detectors; but, these sensors cannotbe used at thermal processing temperatures and have to be positioned adistance away from the tube. This limitation reduces the useablesensitivity. This approach is also described in Tucker, G. S. andWithers, P. M., “Determination of Residence Time Distribution of FoodParticles in Viscous-Food Carrier Fluids using Hall effect sensors”,Technical Memorandum 667, Campden Food and Drink Research Association(CFDRA), Campden, Glos., U.K. (1992), referenced above.

[0016] U.S. Pat. No. 5,261,282, issued to Grabowski et al. on Nov. 16,1993, describes the use of implanted radio frequency transponders tomonitor residence times of simulated pasta particles (macaroni) in acontinuous thermal system. Multiple transponder i.d. signals were usedand density compensation to the carrier fluid density (neutral buoyancy)was applied. The system is limited to large, preferably hollow foodparticle types due to the size and weight of transponder implants.Additionally, transparent (glass or plastic) tube inserts are necessaryto allow for the signal penetration and to enable the detection byexternal detectors.

[0017] Palaniappan et al., “Thermal Process Validated for FoodsContaining Particulates”, Food Technology, Vol. 51, No. 8, (August 1997)pp. 60-68 used essentially the identical tagging and detection system asdescribed by Segner et al. (1989), but implemented density compensationto the carrier fluid density of the food stream. A single magneticimplant type was used. This work was promising in that it produced the aFDA filing, prepared by Tetra Pak Inc., that received a letter of norejection from the FDA. This was the first such letter ever issued bythe FDA for continuous thermal processing of a multi-phase food product.However, this method, as well as the methods described above, uses asingle magnetic tagging implant type and requires that the particleclear the entire observed system or system segment before the nextparticle is inserted to prevent misidentification. Additionally, allsystems using wound coils as sensors are susceptible to occasionalnon-detection due to low sensitivity and problems at lower velocities.

[0018] U.S. Pat. No. 5,021,981 issued to Swartzel et al. on Jun. 4, 1991and in U.S. Pat. No. 5,159,564 issued to Swartzel et al. on Oct. 27,1992 each describe method for determining the thermal history of anobject, such as a particle of food being treated in a food processingapparatus, and thermal memory cells useful in carrying the methods. Thethermal history is determined by detecting changes, after exposure ofthe object to a thermal treatment, in two thermal calibration materialsthat have different activation energies and that are placed in orcoupled to the object.

[0019] Therefore, none of the attempts in the prior art have providedthe food processing industry with a method and system that provide aconservative profile of the behavior of food particles in a continuousthermal flow of a particulate-containing food product in real time andin a cost-effective manner; that do not require the use of excessiveamounts of food product and time; and that function with a variety ofthermal processing systems. Indeed, a suitable detectable particle wouldhave the size and density to provide a conservative residence timemeasurement as compared to the food particle (i.e., potato, beef cube,etc.) of interest, while containing a sufficient level of magneticmaterial loading to enable reliable entry and exit detection underrealistic processing conditions. By “conservative residence timemeasurement”, it is meant that residence time measurement with thehighest likelihood of containing the fastest particle. Such a detectableparticle is lacking in the prior art.

[0020] What is also needed is a method and system that canconservatively model and calculate residence time in continuous thermalprocessing of particulate-containing food products. Such a method andsystem are lacking in the prior art.

DISCLOSURE OF THE INVENTION

[0021] A method of generating a residence time measurement of aparticulate-containing food product while passing the product as acontinuous stream through a thermal processing apparatus is described.The method comprises the steps of: inserting at least one detectableparticle tagged with at least one detectable magnetic implant into thestream at pre-selected intervals; detecting the at least one implantusing at least one sensor located at a detection point downstream from alocation of the inserting of the at least one detectable particle;determining a time of passage of the at least one detectable particle inthe stream using output from the at least one sensor; and generating aresidence time measurement for the stream using the time of passage forthe at least one detectable particle. Alternatively, a plurality ofdetectable particles can be inserted into the stream at pre-selectedintervals, wherein each detectable particle includes a detectablemagnetic implant.

[0022] Preferably, the sensor has a sensitivity such that the sensor iscapable of detecting a magnetic field of at least as low as 0.05oersteds, and can detect the detectable particle when the detectableparticle has a lower speed boundary of zero velocity. The sensor canalso have a sensitivity such that the sensor is capable of detecting amagnetic field ranging from at least as low as 0.05 oersteds to about 20oersteds.

[0023] The method can further comprise providing a detectable particlewherein at least one physical parameter of the particle that effectsbehavior of the particle in the stream is adjusted to provide aconservative residence time measurement. The physical parameter can beselected from a group including, but not limited to, density, size,shape and combinations thereof. The density of the particle ispreferably adjusted to a target density wherein the target density isthat density with the highest likelihood of including a fastestparticle.

[0024] In the method of this invention, the magnetic implant cancomprise a material including, but not limited to, neodymium iron boron,cobalt rare earth, aluminum-nickel, ceramic, organic, plastic-embeddedmetal or ceramic and combinations thereof. Further, the pre-selectedintervals for inserting the detectable particles can be selected tomaximize a number of inserted detectable particles per unit time and tominimize time and quantity of the stream used to generate the residencetime measurement. Additionally, the at least one sensor can be placedproximate to the stream using a gasket.

[0025] The method can further comprise placing additional sensors at thedetection point; and determining the time of passage in the stream forthe at least one detectable particle in the stream using output fromeach sensor. The method can also further comprise placing additionalmagnetic sensors at at least one additional detection point downstreamfrom the location of the inserting of the detectable particles; anddetermining the time of passage in the stream for the at least onedetectable particle in the stream using output from each sensor.

[0026] The method can also further comprise placing additional magneticsensors at a plurality of additional detection points downstream fromthe location of the inserting of the at least one detectable particle;and determining the time of passage in the stream for the at least onedetectable particle in the stream using output from each magneticsensor.

[0027] When a plurality of detectable particles are injected into thestream, the method of this invention can also comprise the step ofcalibrating each of the sensors with a magnetic field of each of thedetectable particles, such that each sensor detects a different range ofmagnetic field strengths of the particles and/or a different range ofmagnetic identifications for the particles.

[0028] Each of the plurality of particles can also include a differentmagnetic implant, such that each particle has a different magneticidentification, as defined herein. The different magnetic implants canvary according to a physical parameter selected from the groupincluding, but not limited to, the number of implants within theparticle, size of implant, shape of implant, mass of implant, magneticmaterial used, location of implant within the particle, and combinationsthereof.

[0029] A system suitable for carrying out the method of this inventionis also described.

[0030] A sensor assembly for detecting a detectable particle used inmeasuring residence time for a particulate-containing food product whilepassing the product as a continuous stream through a thermal processingapparatus is also described. The sensor assembly comprises a gasket andat least one magnetic sensor mounted within the gasket. Alternatively, aplurality of sensors can be mounted within the gasket.

[0031] A combination comprising a detectable particle and a sensor foruse in evaluating thermal treatment for a particulate-containing foodproduct while passing the product as a continuous stream through athermal processing apparatus is also described. The detectable particlecomprises a detectable magnetic implant and a carrier, and the sensor iscapable of detecting a magnetic field of at least as low as 0.05oersteds. The sensor can also be capable of detecting a magnetic fieldranging from at least as low as 0.05 oersteds to about 20 oersteds.

[0032] The particle can further comprise at least one additionalmagnetic implant. The at least one additional magnetic implant candiffer from the other magnetic implant according to a physical parameterincluding, but not limited to, size, shape, mass, magnetic materialused, location within the particle and combinations thereof.

[0033] At least one physical parameter of the particle that affectsbehavior of the particle in the stream can be adjusted to provide aconservative residence time measurement. In this case, the physicalparameter includes, but is not limited to, density, size, shape andcombinations thereof. Indeed, the density of the particle is preferablyadjusted to a target density wherein the target density is that densitywith the highest likelihood of including a fastest particle.

[0034] The magnetic implant of the particle can comprise a materialincluding, but not limited to, neodymium iron boron, cobalt rare earth,aluminum-nickel, ceramic, organic, plastic-embedded metal or ceramic andcombinations thereof. The magnetic implant can have a configurationselected from the group including, but not limited to, a circle, asphere, a tetrahedron, an asterisk, a cross, a cube, a triangle, apyramid, a square, a rectangle, and combinations thereof.

[0035] The carrier component of the particle can comprise materialselected from the group including, but not limited to, polystyrene,copolymers thereof, polypropylene, copolymers thereof, and combinationsof polystyrene, copolymers thereof, polypropylene and copolymersthereof. The carrier can also comprise a container. In this case, thecontainer can further comprise a lid, a body and a gasket, the gasketcooperating with the lid and the body to form a seal between the lid andthe body. The carrier can also comprise an actual food particle.

[0036] The particle can further comprise a cargo component. The cargocomponent can be selected from the group including, but not limited to,an inert material, a thermal memory cell, a microbial load, an actualfood particle, a thermal pill, a thermal insulating material, atransponder and combinations thereof.

[0037] Accordingly, it is an object of this invention to provide amethod and system for generating a residence time measurement of aparticulate-containing food product while passing the product as acontinuous stream through a thermal processing apparatus.

[0038] It is another object of this invention to provide a detectableparticle for use in such a system wherein the size and density of suchparticle has been compensated to provide a conservative residence timemeasurement as compared to the food particle (i.e., potato, beef cube,etc.) of interest, while containing a sufficient level of magneticmaterial loading to enable reliable entry and exit detection underrealistic processing conditions. By “conservative residence timemeasurement”, it is meant that residence time measurement with thehighest likelihood of containing the fastest particle.

[0039] It is a further object of this invention to provide such a methodand system wherein the sensors are sufficiently sensitive and areconfigured to pick up extremely low signal levels.

[0040] It is still a further object of this invention to provide such amethod and system wherein a detectable particle comprises multipleshapes and wherein multiple detectable particles can be used to generatethe residence time measurement.

[0041] It is yet a further object of this invention to provide a methodand system for characterizing residence time for aparticulate-containing food product while passing the product as acontinuous stream through a thermal processing apparatus such thatappropriate velocities and hold times that provide for the killing ofmicroorganisms and their spores in the food product are determined andutilized for the stream.

[0042] It is still another object of this invention to provide a methodand system that can be implemented under normal processing runconditions to evaluate thermal treatment of the stream as a part of theregular quality control procedure for regular production runs, inaddition to facilitating fulfillment of requirements for a processfiling as required by the FDA.

[0043] Some of the objects of the invention having been statedhereinabove, other objects will become evident as the descriptionproceeds, when taken in connection with the accompanying drawings asbest described hereinbelow.

BRIEF DESCRIPTION OF THE DRAWINGS

[0044]FIG. 1 is a cross-sectional view of two of the detectableparticles of the instant invention;

[0045]FIG. 2 is a front elevation view of the detectable particles ofthis invention wherein the particles comprise three differentrepresentative shapes;

[0046]FIG. 3 is a perspective view of a collection of the detectableparticles of this invention wherein the particles comprise fourdifferent representative shapes;

[0047]FIG. 4 is a perspective view of a cubical detectable particle ofthis invention wherein magnetic tracer elements are mounted at aplurality of locations around the particle;

[0048]FIG. 5 is a perspective view of a carrier component of analternative embodiment of the detectable particle of this invention;

[0049]FIG. 6 is a front view of the detectable particle of thisinvention including the carrier component depicted in FIG. 5 and furtherincluding a detectable implant;

[0050]FIG. 7 is a schematic view of the system of this invention;

[0051]FIG. 8 is a schematic cross-sectional view of the system of thisinvention as depicted in FIG. 7;

[0052]FIG. 9A is a schematic of a first alternative embodiment of thesystem of this invention prior to mounting on a thermal processingapparatus;

[0053]FIG. 9B is a schematic of a first alternative embodiment of thesystem of this invention when mounted on a thermal processing apparatus;

[0054]FIG. 10 is a schematic of a second alternative embodiment of thesystem of this invention;

[0055]FIG. 11 is a graphical presentation of giant magneto-resistive(GMR) sensor output characteristics;

[0056]FIG. 12 is a graphical presentation of the time and productrequired to generate a residence time profile in a conventional methodand system as compared to the method and system of this invention;

[0057]FIG. 13 is a graphical presentation of velocity versus densityrelationship at a 40 l/min flow rate;

[0058]FIG. 14 is a graphical presentation of velocity versus densityrelationship at 60 l/min flow rate;

[0059]FIG. 15 is a graphical presentation of velocity versus densityrelationship at 80 l/min flow rate; and

[0060]FIG. 16 is a graphical presentation of the critical density rangedetermined from 27 experimental runs.

DETAILED DESCRIPTION OF THE INVENTION

[0061] In the method and system of this invention, detectable particlesproviding conservative (high velocity) flow characteristics are taggedwith several different sizes and spatial configurations of single ormultiple magnetic implants. By the term “conservative”, it is notnecessarily meant the detectable particle should simulate or mimicexactly the behavior of an actual food particle in the flow. Rather, bythe term “conservative”, it is meant the particle is engineered toprovide the highest probability of detecting the fastest particle in theflow. Stated differently, then, it is an objective of this invention toconservatively simulate or mimic the behavior of an actual foodparticle.

[0062] Thus, the detectable particles used in the method and system arealso an aspect of this invention. By the term “detectable particle” itis meant a particle that includes a tracer or insert component that isdetectable by sensors used in the method and system. The insertcomponent is attached to or integrated into a carrier component ormedium of the particle.

[0063] The particles of this invention have been engineered so thattheir density is compensated to a predetermined level. The particles canbe of uniform size and shape, or can vary in size or shape. Theobjective is to provide a detectable particle having the size and/ordensity to provide a conservative residence time measurement as comparedto the food particle (i.e., potato, beef cube, etc.) of interest, whilecontaining a sufficient level of magnetic material loading to enablereliable entry and exit detection under realistic processing conditions.By “conservative residence time measurement”, it is meant that residencetime measurement with the highest likelihood of containing the fastestparticle.

[0064] Thus, in the preferred embodiment, when it is said that thedensity of the particle is compensated to a predetermined or targetlevel, it is meant that density which provides for a conservativeresidence time measurement. Further, choices for particle size, shapeand density adjustment as presented herein are made with the objectiveof providing a conservative residence time measurement in mind.

[0065] Each detectable particle preferably comprises a carriercomponent, a detectable component, and a cargo component. Thus, the massof the carrier component plus the mass of the detectable component plusthe mass of the cargo component equals the mass of the particle.

[0066] Referring now to FIGS. 1-13, wherein like reference numeralsrefer to like parts throughout, and particularly referring to FIG. 1,the detectable particle of this invention is generally referred to as10. Particle 10 comprises a carrier component 12 that is depicted as ahollow container.

[0067] Carrier 12, which is designated with diagonal hatching in FIG. 1,comprises a material that is susceptible to precision manufacturingthrough machining and insertion molding. It is also preferred thatcarrier 12 be stable at ultra high temperatures. Additionally, carrier12 can also be reusable so as to be amenable to multiple applications.Suitable examples of material for carrier 12 include polypropylene,polypropylene copolymer, or combinations thereof. The preferred densityof the material is approximately 0.9 g/ml.

[0068] Continuing on FIG. 1, particle 10 further comprises detectablecomponents 14. Detectable components 14 comprise magnetic implants thatare embedded within the walls of carrier 12. In FIG. 1, magneticimplants 14 are designated by circles with horizontal hatching.

[0069] Magnetic implants 14 can comprise any magnetic material, whethercurrently known or subsequently discovered. An example of a suitablematerial can be selected from the group including, but not limited to,neodymium iron boron, cobalt rare earth, aluminum-nickel, ceramic,organic, plastic-embedded metal and ceramic and combinations thereof.Other examples would be apparent to one having ordinary skill in theart.

[0070] It is noted that magnetic implants 14 can be in any suitableshape and configuration. Examples include, but are not limited to,square, block, triangular, pyramidal, spherical, circular, tetrahedron,needle, coil and combinations thereof. Further, while the implants 14are shown in FIG. 1 as embedded in the walls of carrier 12, implants 14can also be placed within the internal void space of the carrier 12, orotherwise suitably mounted within carrier 12.

[0071] Magnetic implants 14 preferably comprise neodymium iron boron.Neodymium iron boron is a preferred example because it is commerciallyavailable in particles of various shapes and sizes and has a highmagnetic field strength per unit mass. A commercial source of suchmagnets is Permag, a division of The Dexter Corporation, 1150 KiferRoad, Suite 201, Sunnyvale, Calif. 94086. A particularly suitableexample of implant 14 is available from Permag as Part Number 9054248.This part number is particularly suitable because it represents thesmallest and weakest magnetic implant 14 that can be detected by thesensors used in the method and system of this invention. Therefore, thispart number is particularly suited for use in the particle and systemconfigurations described more fully below. The preferred implant 14 isalso described in Table 1. TABLE 1 Preferred example of implant 14 -Available from Permag, 1150 Kifer Road, Suite 201, Sunnyvale, CA 94036as Part Number 9054248, neodymium iron boron, mass 0.035 g.

[0072] In each embodiment of the particle 10 described herein, the massand shape of each magnetic implant 14 is preferably chosen according toa desired magnetic identification (also referred to herein as “magnetici.d.”) for a particle 10. By the term “magnetic identification” is meantthat magnetic field or fields generated by individual magnetic implantsor by combinations of multiple magnetic implants included withinparticle 10 such that an individual particle 10 can be detectedaccording to the magnetic fields generated by the implant or implants14.

[0073] For example, the mass of implant 14 can be as small as can bedetected by suitable sensors as described herein, and can be increasedaccording the size and mass of the actual food particle that thepractitioner is trying to conservatively simulate or mimic. Generally,the magnetic field of an implant 14 increases as the mass of the implant14 increases. Therefore, different magnetic fields, and thus, differentmagnetic i.d.s can be produced by including implants of varying mass indifferent particles 14. Alternatively, a different magnetic i.d. foreach particle 10 in a group of particles 10 can be produced by varyingthe number of implants 14 present within each particle 10. The implants14 can have the same mass or can vary in mass. It should be pointed outthat extremely heavy implants 14 (mass approaching 1 gram or greater)can overload the more sensitive GMR sensors used in the method andsystem of this invention described herein below, and therefore, shouldbe used with caution.

[0074] Furthermore, a magnetic i.d. can be produced using a particularshape of implant 14 because of the signal produced by the shape when itis detected by the sensors described herein. Suitable shapes include,but are not limited to, cubical, rectangular or box-shaped, spherical,cylindrical, tetrahedron, circular, square, asterisk, cross, needle,coil, rectangular, triangular, and combinations thereof.

[0075] Continuing with reference to FIG. 1, detectable particle 10 alsopreferably includes a cargo component 16. Cargo component 16 optionallycomprises an inoculum pack 18 of a suitable microorganism and itsspores. When cargo component 16 includes an inoculum pack 18, thethermal conductivity of particle 10 must be lower than that of an actualfood particle so as to provide a conservative characterization of theamount of heat received by the inoculum pack 18 when it is run throughthe flow. Inoculum pack 18 is designated by spaced dashes in FIG. 1.

[0076] After particle 10 is run through a thermal processing system,inoculum pack 18 can be used to determine the effectiveness of thesystem in killing microorganisms and to determine if particle 10 stayedin the system for a sufficient length of time at sufficient temperatureto kill microorganisms and their spores. Thus, inoculum pack 18 isuseful in evaluating thermal treatment of the stream ofparticulate-containing food product. Inoculum pack 18 can be culturedusing well-known techniques, such as plating on a suitable culturemedium, to see if microorganisms or their spores are present insufficient numbers to grow when cultured.

[0077] Continuing with reference to FIG. 1, cargo component 16 furthercomprises thermal memory cells 20. Suitable examples of thermal memorycells 20 include those described in U.S. Pat. No. 5,159,564 and U.S.Pat. No. 5,021,981, the contents of each of which are hereinincorporated by reference, as well as a time/temperature integratorcell. Thermal memory cells 20 are designated by rectangles with diagonalhatching in FIG. 1.

[0078] Thermal memory cells 20 are used to characterize thetime-temperature profile of a thermal processing system. This enablesthe practitioner to determine if particles 10 were exposed to anappropriate temperature for an appropriate length of time as they passedthrough the system. Thus, thermal memory cells 20 are useful inevaluating thermal treatment of the stream of particulate-containingfood product.

[0079] Cargo component 16 can include an inert material for densitycompensation, according to the density calculations described more fullybelow. Suitable examples of inert components include polypropylenebeads, silica gel beads, non-magnetic stainless steel beads, a thermalinsulating material and combinations thereof. Examples of suitablethermal insulating materials include polyurethane foam, among others.Thermal insulating materials are included to protect the magneticimplant 14 from the heat of the thermal processing system, as it iswell-known that magnets are weakened by high temperature.

[0080] Additionally, the use of a thermal insulating material providesfor a particle 10 with a thermal conductivity lower than that of anactual food particle so as to provide a conservative characterization ofthe amount of heat received by the inoculum pack 18 and thermal memorycells 20 when they are run through the flow in particle 10. Thus, othersuitable examples of thermal insulating materials include polymers andpolymer gels.

[0081] Cargo component 16 can also comprise an actual food product orcan comprise a transponder such as one described in U.S. Pat. No.5,261,282, issued to Grabowski et al. on Nov. 16, 1993, the contents ofwhich are herein incorporated by reference. Cargo component 16 can alsocomprise a thermal pill, as described in NASA Tech Briefs, June 1990, p.106.

[0082] Referring now to FIG. 2, carrier 12 comes in a variety of shapes.Each carrier 12 includes a lid 22 and a body 24. Lids 22 can bethreadingly secured to body 24 via threads 26. Alternatively, lids 22can be permanently secured to body 24. As an additional alternative, anadhesive layer 28 can be used to fixedly secure lid 22 to body 24.Adhesive layer 28 can optionally comprise an ultra-violet activatedadhesive. Additionally, gaskets (not shown in FIG. 2) can be used toprovide a better seal between lid 22 and body 24.

[0083] Referring now to FIGS. 3 and 4, an alternative embodiment ofparticle 10 is described. The carrier component 12 of this embodiment ofparticle 10 comprises a solid mass, preferably comprising polypropyleneor polystyrene. As best seen in FIG. 3, carrier components 12 are formedin a variety of shapes, including cubical, rectangular or box-shaped,spherical and cylindrical. Indeed, the shapes can be chosen to simulatefood particle shapes either nearly exactly or conservatively. In thiscase, each carrier component 12 is also dimensioned according to actualfood particle size specifications in order to facilitate conservativesimulation of an actual food particle's behavior in a thermal flow.

[0084] In the embodiment depicted in FIGS. 3 and 4, detectablecomponents 14 comprise magnetic implants. Referring now to FIG. 4,magnetic implants 14 are mounted using a suitable adhesive into boresdrilled into carrier component 12. As best seen in FIG. 4, magneticimplants 14 are mounted at corners and/or at the centers of sides of thecubical carrier component 12. This approach provides for fourteen (14)placement points for implants 14. These placement points can be mademore specific by placing similar implants at corresponding oppositelocations. Stated differently, particle 10 can include seven (7) pairedsets of implants 14. This particular configuration provides forpotentially seven (7) different magnetic identifications. Thus, the term“magnetic identification” also includes the magnetic fields generated bycombinations of multiple magnetic implants included within particle 10.

[0085] Referring now to FIGS. 5 and 6, another alternative embodiment ofparticle 10 is described. The carrier component 12 of this embodiment ofparticle 10 comprises a hollow tube, preferably comprising polypropyleneor polystyrene. The tube can be of varying diameter, including ¼ ofinch, ⅛ of inch and {fraction (1/16)} of an inch. The appropriate lengthand diameter of the tube are chosen according to actual food particlesize specifications in order to facilitate conservative simulation of anactual food particle's behavior in a thermal flow.

[0086] As best seen in FIG. 6, a detectable component 14 comprising amagnetic implant is placed into carrier component 12 and the ends of thecarrier component 12 are sealed to form particle 10.

[0087] While the foregoing examples present examples of carrier 12 thatcomprise polypropylene and polystyrene, it is also noted that carrier 12can comprise an actual food particle.

[0088] Determination of Density to be Used in Simulated Particle DensityCompensation

[0089] One of the most important particle properties affecting itsbehavior (especially velocity and the resulting residence time) inmulti-phase flow during thermal processing of the particulate containingfoods is density.

[0090] Before detectable particle 10 can be inserted into a thermalflow, the target density of the particle must be determined and theactual density of the particle must be adjusted to match the targetdensity. The objective in the preferred embodiment is to provide adetectable particle with a density that provides a conservativeresidence time measurement as compared to the food particle (i.e.,potato, beef cube, etc.) of interest, while containing a sufficientlevel of magnetic material loading to enable reliable entry and exitdetection under realistic processing conditions. By “conservativeresidence time measurement”, it is meant that residence time measurementwith the highest likelihood of containing the fastest particle. Thus, inthe preferred embodiment of the invention, when it is said that thedensity of the particle is compensated to a target level, it is meantthat density which provides for a conservative residence timemeasurement.

[0091] The critical density of particle 10 is defined as the particledensity range with the highest likelihood of containing the fastestparticle, as determined experimentally for each system or systemcomponent. The critical density is dependent to an extent on fluiddensity, and not particle density. For the standard horizontal holdtubes often used in continuous thermal processing, the critical densityis near to slightly lower than carrier fluid density. For othergeometries of the standard continuous thermal processing equipment, suchas scraped surface heat exchanger (SSHE) or helical tubes, the criticaldensity is dependent on the geometry/inclination of the equipment.

[0092] Due to thermal, spatial and temporal variations of density causedby thermal expansion, denaturation of proteins, and release andtransport of fats, liquids and gases it is very difficult to monitor oreven estimate the density of particles during the process. It isadditionally difficult to monitor the relationship of solid particledensity to carrier fluid density in situ since all of the abovevariations at the same time affect the density and density dynamics ofthe carrier fluid. Thus, no specific density range or ratio can beeliminated from the range potentially occurring during the processing.

[0093] It is thus desirable to determine the velocities and residencetimes of a range of simulated particles with various densities,preferably including the initial particle density, the initial carrierfluid density, the final particle density, the final carrier fluiddensity and their maximal and minimal values achieved during processingdetermined either experimentally or theoretically; and a selectedadditional range above and below the minimum and maximum values thusobtained.

[0094] A simulated particle population is generated evenly covering theestablished range of densities by individual particle density adjustmentusing the carrier-implant-cargo calculation principles presented inTable 2 below.

[0095] The velocity/residence time measurements are then performed byinserting the particles with various densities into the product streamand measuring the entry and exit times at selected locations in theprocess.

[0096] The resulting range of velocities and residence times thusincorporates all the reasonably expected residence time variabilitydependent on particle density. The method is device and processindependent, i.e., is applicable to any process geometry and operatingconditions.

[0097]FIGS. 13 through 16 graphically present the results of criticaldensity experiments. FIG. 13 is a graphical presentation of velocityversus density relationship at a 40 l/min flow rate. FIG. 14 is agraphical presentation of velocity versus density relationship at 60l/min flow rate. FIG. 15 is a graphical presentation of velocity versusdensity relationship at 80 l/min flow rate. FIG. 16 is a graphicalpresentation of the critical density range determined from 27experimental runs.

[0098] Critical density is therefore defined as the particle densityvalue or density range with the highest likelihood of containing thefastest particle. In the preferred embodiment of the invention, thetarget density is defined as the arithmetic mean of the critical densityrange and can then be used as a basis for density compensation ofsimulated particles to be used for the residence time measurement sothat the residence time measurement will be conservative.

[0099] The target density can be used to determine the mass of cargocomponent 16 to be included in carrier 12 for density compensation.First of all, total mass is calculated by multiplying target densitytimes particle volume. Then, cargo mass is determined by subtractingfrom the total mass of the particle the container mass and the implantmass. This calculation is set forth in Table 2 below. TABLE 2 Cargo masscalculation for density compensation: Total mass = Target density *Particle volume Cargo mass = Total mass − Container mass − Implant mass

[0100] Minimum Insertion Delay Calculations for Particle Residence TimeMeasurement in Multi-Phase Flow During Thermal Food Processing

[0101] Once the target density is determined and particle density isadjusted accordingly, the particle is ready for insertion into the flowof food to the characterized. The detectable particles are inserted intoa food product flowing through a thermal system at pre-selectedintervals. The insertion delay intervals are selected to maximize thenumber of inserted detectable particles per unit time and minimize thetime and quantity of food product used for the required measurements.Although an insertion device can be used if desired, no specialinsertion device is needed. The first detectable particle can be simplyinserted into a hopper that is in communication with the stream of foodand the timing delay for the remaining particles, as presented in theTables 2b through 2f below, can be started at the time of system entrydetection.

[0102] An insertion device with controlled delay or feedback triggerthat is calibrated to activate according to the interval delaysdescribed in Tables 2b through 2f below can also be used to control theinsertion timing. Such a device is placed in communication with acontinuous flow to accomplish insertion.

[0103] Another example of an insertion device can be found in U.S. Pat.No. 5,261,282, issued to Grabowski et al. on Nov. 16, 1993, the contentsof which are herein incorporated by reference, as injection station 37.

[0104] The injection delay intervals are selected based on severalassumptions:

[0105] 1. Several different particle magnetic identifications are usedin the residence time measurement.

[0106] 2. Magnetic tagging via implants and detection via external,non-obstructing sensors are the preferred means of i.d. assignment andi.d. recognition respectively.

[0107] 3. The goal is to minimize the expenditure in product and timewhile enabling a high number of particle residence time measurements.

[0108] The standard methodology employing magnetically tagged particlesrequires that the exit of the previous particle be positively confirmed(each particle clears the entire system) before the next tagged particleis inserted to prevent misidentification.

[0109] In applicants method, the calculation of the minimum insertiondelay allows the insertion of the following particle before the previousparticle has cleared the system by insuring that the delay is sufficientto avoid the meeting of identical i.d. particles. Stated differently,after inserting a particle having a magnetic i.d. 1, particle havingmagnetic i.d.s 2, 3, 4, etc. can be inserted into the flow one afteranother during the pre-selected interval before the next particle havingmagnetic i.d. 1 is inserted. Thus, the method and system of thisinvention provide for the presence of a plurality of detectableparticles in the stream at one time.

[0110] The major principle of applicants' method is that two particleswith identical magnetic i.d.s should never be allowed to get in contactor get ahead of one another at any point in the system. Thus, for thebasic minimum insertion delay interval it is assumed that thetheoretically fastest particle always follows the theoretically slowestparticle in the system. The insertion delay interval is then calculatedso that it is sufficient to prevent the theoretically fastest particlefrom ever catching up with the theoretically slowest particle (with theidentical i.d.).

[0111] Tables 2a through 2f present calculations of minimum requireddelay time between successive particle injections for a range ofoperating conditions. All calculations are based on a 2 in. (5.08 cm)internal diameter hold tube.

[0112] Table 2a demonstrates the product usage and time needed toperform the residence time measurements by the standard methodology.

[0113] Table 2b illustrates the principle of calculated time delayinterval using a single type of magnetic implant identification,establishing a required time delay needed to avoid the contact of twosubsequent particles with the same magnetic identification.

[0114] Tables 2c, 2d, 2e and 2f illustrate the advantages (savings intime and product) when multiple (2, 3, 4, and 5 respectively) magnetici.d.s are used for particle tagging. The insertion delay interval isthus divided by 2, 3, 4 and 5 respectively while maintaining the sameminimum insertion delay between two particles having the same magnetici.d.s.

[0115] Tables 2a through 2f describe three sets of runs at flow rates of40, 60 and 80 liters per minute and in tubes of 40, 60 and 80 meters inlength. Thus, each table includes nine (9) entries. Due to marginrequirements and character size considerations, the tables have beenassembled in segments below. Each line of data within each table beginswith, or falls below, a number between 1 and 9 to correspond with eachrun. Thus, the table segments should be reviewed with this numberingsystem in mind. TABLE 2A PRODUCT USAGE AND TIME FOR PRIOR ART METHODSTIME AND PRODUCT NEEDED FOR ONE RUN (400 TIME AND PRODUCT NEEDED Avg.fluid Avg. time DETECTABLE FOR THREE RUNS (3 * 400 Flow rates velocityTube of flight PARTICLES) DETECTABLE PARTICLES) [l/min] [m³/s] [m/s] [m][s] TIME [s] TIME [h] PRODUCT [l] TIME [h] PRODUCT [l] 1. 40 0.0006670.32892 40 121.61 48643.92 13.5122 32429.27866 40.53659833 97287.835992. 40 0.000667 0.32892 60 182.41 72965.83 20.2683 48643 9179960.80489749 145931.754 3. 40 0.000667 0.32892 80 243.22 97287.84 27.024464858.55732 81.07319666 194575.672 4. 60 0.001 0.49338 40 81.07332429.28 9.008133 32429.27866 27.02439889 97287.83599 5. 60 0.0010.49338 60 121.61 48643.92 13.5122 48643.91799 40.53659833 145931.754 6.60 0.001 0.49338 80 162.15 64858.56 18.01627 64858.55732 54.04879777194575.672 7. 80 0.001333 0.65784 40 60.805 24321.96 6.7561 32429.2786620.26829916 97287.83599 8. 80 0.001333 0.65784 60 91.207 36482.9410.13415 48643.91799 30.40244875 145931.754 9. 80 0.001333 0.65784 80121.61 48643.92 13.5122 64858.55732 40.53659833 194575.672

[0116] TABLE 2B PROGRAMMED INSERTION DELAY SINGLE MAGNETIC PARTICLETYPE) MAXIMUM THEORETICAL DETECTABLE MINIMUM THEORETICAL PARTICLE VEL.DETECTABLE PARTICLE (avg. fluid *2) VEL. Avg. fluid Time of (avg. fluidvel.) MINIMUM Flow rates velocity Tube flight Time of DELAY [l/min][m³/s] [m/s] [m] [m/s] [s] [m/s] flight [s] [s] 1. 40 0.000667 0.3289240 0.6578 60.80 0.32892 121.61 60.80 2. 40 0.000667 0.32892 60 0.657891.21 0.32892 182.41 91.21 3. 40 0.000667 0.32892 80 0.6578 121.610.32892 243.22 121.61 4. 60 0.001 0.49338 40 0.9868 40.54 0.49338 81.0740.54 5. 60 0.001 0.49338 60 0.9868 60.80 0.49338 121.61 60.80 6. 600.001 0.49338 80 0.9868 81.07 0.49338 162.15 81.07 7. 80 0.0013330.65784 40 1.3157 30.40 0.65784 60.80 30.40 8. 80 0.001333 0.65784 601.3157 45.60 0.65784 91.21 45.60 9. 80 0.001333 0.65784 80 1.3157 60.800.65784 121.61 60.80 TIME AND PRODUCT NEEDED FOR ONE RUN (400 DETECTABLETIME AND PRODUCT NEEDED FOR THREE PARTICLES) RUNS (3 * 400 DETECTABLEPARTICLES) TIME [s] TIME [hr] PRODUCT [l] TIME [hr] PRODUCT [l] 1.24321.96 6.7561 16214.63933 20.26829916 48643.91799 2. 36482.94 10.1341524321.959 30.40244875 72965.87699 3. 48643.92 13.5122 32429.2786640.53659833 97287.83599 4. 16214.64 4.504066 16214.63933 13.5121994448643.91799 5. 24321.96 6.7561 24321.959 20.26829916 72965.87699 6.32429.28 9.008133 32429.27866 27.02439889 97287.83599 7. 12160.983.37805 15214.63933 10.13414958 48643.91799 8. 18241.47 5.06707524321.959 15.20122437 72965.87699 9. 24321.96 6.7561 32429.2786620.26829916 97287.83599

[0117] TABLE 2C PROGRAMMED INSERTION DELAY (2 MAGNETIC PARTICLE I.D.s)MAXIMUM THEORETICAL MINIMUM THEORETICAL DETECTABLE PARTICLE DETECTABLEPARTICLE Avg. VEL. VEL. fluid (avg. fluid *2) (avg. fluid vel.) Flowrates velocity Tube Time of Time of MINIMUM DELAY [l/min] [m³/s] [m/s][m] [m/s] Flight [s] [m/s] flight [s] [s] 1. 40 0.000667 0.32892 400.6578 60.80 0.32892 121.61 60.80 2. 40 0.000667 0.32892 60 0.6578 91.210.32892 182.41 91.21 3. 40 0.000667 0.32892 80 0.6578 121.61 0.32892243.22 121.61 4. 60 0.001 0.49338 40 0.9868 40.54 0.49338 81.07 40.54 5.60 0.001 0.49338 60 0.9868 60.80 0.49338 121.61 60.80 6. 60 0.0010.49338 80 0.9868 81.07 0.49338 162.15 81.07 7. 80 0.001333 0.65784 401.3157 30.40 0.65784 60.80 30.40 8. 80 0.001333 0.65784 60 1.3157 45.600.65784 91.21 45.60 9. 80 0.001333 0.65784 80 1.3157 60.80 0.65784121.61 60.80 TIME AND PRODUCT NEEDED FOR ONE RUN TIME AND PRODUCT NEEDED(400 DETECTABLE FOR THREE RUNS (3 * 400 MINIMUM DELAY/2 PARTICLES)DETECTABLE PARTICLES) [s] TIME [s] TIME [h] PRODUCT [l] TIME [hr]PRODUCT [l] 1. 30.40 12160.98 3.37805 8107.319666 10.13414958 24321.9592. 45.60 18241.47 5.067075 12160.9795 15.20122437 36482.9385 3. 60.8024321.96 6.7561 16214.63933 20.26829916 48643.91799 4. 20.27 8107.322.252033 8107.319666 6.756099721 24321.959 5. 30.40 12160.98 3.3780512160.9795 10.13414958 36482.9385 6. 40.54 16214.64 4.504066 16214.6393313.51219944 48643.91799 7. 15.20 6080.49 1.689025 8107.3196665.067074791 24321.959 8. 22.80 9120.731 2.533537 12160.9795 7.60061218636482.9385 9. 30.40 12160.98 3.37805 16214.63933 10.13414958 48643.91799

[0118] TABLE 2D PROGRAMMED INSERTION DELAY (3 MAGNETIC PARTICLE I.D.s)MINIMUM MAXIMUM THEORETICAL THEORETICAL DETECTABLE DETECTABLE PARTICLEVEL. PARTICLE VEL. (avg. fluid vel.) Avg. fluid (avg. fluid *2) Time ofMINIMUM MINIMUM Flow rates velocity Tube Time of flight DELAY DELAY/3[l/min] [m³/s] [m/s] [m] [m/s] flight [s] [m/s] [s] [s] [s] 1. 400.000667 0.32892 40 0.6578 60.80 0.32892 121.61 60.80 20.27 2. 400.000667 0.32892 60 0.6578 91.21 0.32892 182.41 91.21 30.40 3. 400.000667 0.32892 80 0.6578 121.61 0.32892 243.22 121.61 40.54 4. 600.001 0.49338 40 0.9868 40.54 0.49338 81.07 40.54 13.51 5. 60 0.0010.49338 60 0.9868 60.80 0.49338 121.61 60.80 20.27 6. 60 0.001 0.4933880 0.9868 81.07 0.49338 162.15 81.07 27.02 7. 80 0.001333 0.65784 401.3157 30.40 0.65784 60.80 30.40 10.13 8. 80 0.001333 0.65784 60 1.315745.60 0.65784 91.21 45.60 15.20 9. 80 0.001333 0.65784 80 1.3157 60.800.65784 121.61 60.80 20.27 TIME AND PRODUCT NEEDED FOR ONE RUN (400DETECTABLE TIME AND PRODUCT NEEDED FOR THREE PARTICLES) RUNS (3 * 400DETECTABLE PARTICLES) TIME TIME PRODUCT TIME PRODUCT [s] [hr] [l] [hr][l] 1. 8107.32 2.252033 5404.879777 6.756099721 16214.63933 2. 12160.983.37805 8107.319666 10.13414958 24321.959 3. 16214.64 4.50406610809.75955 13.51219944 32429.27866 4. 5404.88 1.501355 5404.8797774.504066481 16214.63933 5. 8107.32 2.252033 8107.319666 6.75609972124321.959 6. 10809.76 3.002711 10809.75955 9.008132962 32429.27866 7.4053.66 1.126017 5404.879777 3.378049861 16214.63933 8. 6080.49 1.6890258107.319666 5.06707471 24321.959 9. 8107.32 2.252033 10809.759556.756099721 32429.27866

[0119] TABLE 2E PROGRAMMED INSERTION DELAY (4 MAGNETIC PARTICLE I.D.s)MAXIMUM MINIMUM THEORETICAL THEORETICAL DETECTABLE DETECTABLE PARTICLEVEL. PARTICLE VEL. Avg. (avg. fluid *2) (avg. fluid vel.) fluid Time ofTime of MINIMUM MINIMUM Flow rates velocity Tube flight flight DELAYDELAY/4 [l/min] [m³/s] [m/s] [m] [m/s] [s] [m/s] [s] [s] [s] 1. 400.000667 0.32892 40 0.6578 60.80 0.32892 121.61 60.80 15.20 2. 400.000667 0.32892 60 0.6578 91.21 0.32892 182.41 91.21 22.80 3. 400.000667 0.32892 80 0.6578 121.61 0.32892 243.22 121.61 30.40 4. 600.001 0.49338 40 0.9868 40.54 0.49338 81.07 40.54 10.13 5. 60 0.0010.49338 60 0.9868 60.80 0.49338 121.61 60.80 15.20 6. 60 0.001 0.4933880 0.9868 81.07 0.49338 162.15 81.07 20.27 7. 80 0.001333 0.65784 401.3157 30.40 0.65784 60.80 30.40 7.60 8. 80 0.001333 0.65784 60 1.315745.60 0.65784 91.21 45.60 11.40 9. 80 0.001333 0.65784 80 1.3157 60.800.65784 121.61 60.80 15.20 TIME AND PRODUCT NEEDED FOR ONE RUN TIME ANDPRODUCT NEEDED FOR THREE (400 DETECTABLE RUNS (3 * 400 DETECTABLEPARTICLES) PARTICLES) PRODUCT TIME PRODUCT TIME [s] TIME [hr] [l] [hr][l] 1. 6080.49 1.689025 4053.659833 5.067074791 12160.9795 2. 9120.732.533537 6080.489749 7.600612186 18241.46925 3. 12160.98 3.378058107.319666 10.13414958 24321.959 4. 4053.66 1.126017 4053.6598333.378049861 12160.9795 5. 6080.49 1.689025 6080.489749 5.06707479118241.46925 6. 8107.32 2.252033 8107.319666 6.756099721 24321.959 7.3040.24 0.844512 4053.659833 2.533537395 12160.9795 8. 4560.37 1.2667696080.489749 3.800306093 18241.46925 9. 6080.49 1.689025 8107.3196665.067074791 24321.959

[0120] TABLE 2F PROGRAMMED INSERTION DELAY (5 MAGNETIC PARTICLE I.D.s)MAXIMUM THEORETICAL MINIMUM THEORETICAL DETECTABLE DETECTABLE PARTICLEPARTICLE VEL. VEL. (avg. fluid *2) (avg. fluid *2) Avg. fluid Time ofTime of MINIMUM Flow rates velocity Tube flight flight DELAY [l/min][m³/s] [m/s] [m] [m/s] [s] [m/s] [s] [s] 1. 40 0.000667 0.32392 400.6578 60.80 0.32892 121.61 60.80 2. 40 0.000667 0.32892 60 0.6578 91.210.32892 182.41 91.21 3. 40 0.000667 0.32892 80 0.6578 121.61 0.32892243.22 121.61 4. 60 0.001 0.49338 40 0.9868 40.54 0.49338 81.07 40.54 5.60 0.001 0.49338 60 0.9868 60.80 0.49338 121.61 60.80 6. 60 0.0010.49338 80 0.9868 81.07 0.49338 162.15 81.07 7. 80 0.001333 0.65784 401.3157 30.40 0.65784 60.80 30.40 8. 80 0.001333 0.65784 60 1.3157 45.600.65784 91.21 45.60 9. 80 0.001333 0.65784 80 1.3157 60.80 0.65784121.61 60.80 TIME AND PRODUCT NEEDED FOR ONE RUN TIME AND PRODUCT NEEDEDFOR (400 DETECTABLE THREE RUNS (3 * 400 DETECTABLE MINIMUM PARTICLES)PARTICLES) DELAY/5 TIME TIME PRODUCT TIME PRODUCT [s] [s] [hr] [l] [hr][l] 1. 12.16 4864.39 1.35122 3242.927866 4.053659833 9728.783599 2.18.24 7296.59 2.02683 4864.391799 6.080489749 14593.1754 3. 24.329728.78 2.70244 6485.855732 8.107319666 19457.5672 4. 8.11 3242.930.900813 3242.927866 2.702439889 9728.783599 5. 12.16 4864.39 1.351224864.391799 4.053659833 14593.1754 6. 16.21 6485.86 1.801627 6485.8557325.404879777 19457.5672 7. 6.08 2432.20 0.67561 3242.927866 2.0268299169728.783599 8. 9.12 3648.29 1.013415 4864.391799 3.040244875 14593.17549. 12.16 4864.39 1.35122 6485.855732 4.053659833 19457.5672

[0121] Detection and Identification of Particles in a Continuous ThermalProcess

[0122] Detection and identification of particles 10 can be accomplishedby using a variety of magnetic sensors. A copper coil sensor is onesuitable example. Copper coil sensors have medium sensitivity and arebased on magnetic flux change. A minimum particle velocity is requiredfor detection.

[0123] Hall effect sensors are also acceptable, as the sensors aremedium/high sensitivity and can detect changes in magnetic flux undertemperature conditions up to 110° C.

[0124] However, the preferred magnetic sensor relies on the giantmagneto-resistive (GMR) phenomenon. This effect is found in metallicthin films comprising magnetic layers a few nanometers thick separatedby equally thin non-magnetic layers. A large decrease in the resistanceof these films is observed when a magnetic field is applied. Thus,magnetic sensors including GMR materials can be used to detect themagnetic fields present in the detectable particles.

[0125] The GMR sensor is very sensitive and can operate at temperaturesranging up to at least 150° C. It is also inexpensive and very small. Agraph of GMR sensor output characteristics is set forth in FIG. 11. SeeGMR Sensor Application Notes, available from Nonvolatile Electronics,Incorporated (NVE), 11409 Valley View Road, Eden Prairie, Minn.55344-3617.

[0126] Single or multiple magnetic sensors are located at detectionpoints downstream from the detection location. Time of passage isdetermined for each tagged particle from the detector response at eachlocation. The outputs from magnetic sensors are used in combination withmagnetic implant configuration and insertion delay time to identify eachinserted particle within a sequence of single or multiple magneticidentification configurations. Using multiple magnetic identifications,time and product quantity required for the three replicants of 400particle residence measurement can be reduced by 90% or more.

[0127] The method and system of this invention can be used with avariety of processing configurations and under a variety of processparameter settings. It is particularly appropriate for systems includingtube-type heat exchangers (helical heat exchangers, ribbed tube heatexchangers, etc.) but can be used with any existing processingequipment.

[0128] Referring now to FIGS. 7 and 8, a preferred sensor configurationis described. A segment 32 of pipe suitable for use in a continuousthermal processing apparatus is fitted with a gasket 36 at coupling 38.Preferably, pipe 32 comprises sanitary stainless steel. A continuousthermal processing apparatus is described in U.S. Pat. No. 5,261,282,issued to Grabowski et al. on Nov. 16, 1993, the contents of which areherein incorporated by reference. Such an apparatus typically includesone or more heating tubes, one or more holding tubes, and one or morecooling tubes, as well as suitable components to package the productafter heat treatment. It is contemplated then that pipe 32 can beincluded as a section within any length of heating, holding or coolingtube. Moreover, as FIG. 7 is schematic, it is also contemplated thatpipe 32 represents all three sections, heating, holding and cooling, ofa standard apparatus.

[0129] Gasket 36 comprises a material suitable for use in a continuousthermal processing apparatus. As described herein, gasket 36 includessensors 40. A battery 34, or other appropriate DC power source, isoperatively connected to sensors 40 to provide appropriate inputvoltages.

[0130] Gasket 36 is preferably in contact with the flow. The sensitivityof detection sensors 40, here GMR sensors, is enhanced by theirplacement within gasket 36. A preferred sensor 40 is available as PartNumber AA002-02 (previously Part Number NVSSB15S) from NonvolatileElectronics, Incorporated (NVE), 11409 Valley View Road, Eden Prairie,Minn. 55344-3617. This sensor is capable of detecting a magnetic fieldat least as low as 0.05 oersteds. Further, this sensor can detect amagnetic field ranging in strength from at least as low as 0.05 oerstedsto about 20 oersteds.

[0131] As best seen in FIG. 8, sensors 40 are disposed around the innerperiphery of gasket 3G, thus placing them proximate to the flow of foodwithout placing an obstruction within the flow. This configurationeliminates the need to sense through the wall of stainless steel pipe 32(see FIG. 7).

[0132] A computer acquisition system 42 including appropriate softwareis used to monitor and register signals originating at each sensor 40.This output is used for timing and identification on-line and for postprocess analyses. Computer acquisition system 42 preferably comprises aPENTIUM® microprocessor personal computer (PC) including a KeithleyMetrobyte DAS1800HC package with TESTPOINT™ software. TESTPOINT™software is a commercially available package that can receive sensorsignals, process them and output the signals in a suitable form, such asgraphically. TESTPOINT™ software is designed to be programmable so thatthe user can customize it according to the user's needs.

[0133] Embodiment of System Including Sensors Calibrated to MagneticI.D. Ranges of Particles

[0134] Referring now to FIGS. 9A and 9B, an alternative configurationfor sensors 40 in the method and system of this invention is depicted.GMR sensors 40 a, 40 b and 40 c are wrapped around pipe 32 using belt 33at test point locations. Belt 33 can be tied on, clipped on, or strappedon using a hook-and-eye type closure sold under the registered trademarkVELCRO®. Flexible printed circuits, which are commercially available,can also be used to mount sensors 40.

[0135] In this embodiment, particles 10 are inserted via an insertionmeans like hopper 30. GMR sensors 40 a, 40 b and 40 c are connected tobatteries (or other appropriate DC power sources) 44, 46 and 48,respectively, that provide different input voltages so that inputvoltages that alternate between adjacent sensors are provided. GMRsensors 40 a, 40 b and 40 c are also mounted in straps 50 that includeflux concentrating material 52 so that alternating sensors pick updifferent magnetic field strengths. Thus, the alternating input voltageand/or flux concentrator strengths can be adjusted to magneticidentifications comprising individual magnetic field strengths forparticles 10 introduced into a continuous thermal processing system.Thus, the term “magnetic identifications” also comprises individualmagnetic field strengths for particles 10. Signals from the nowcustomized sensors 40 a, 40 b and 40 c are transmitted to computeracquisition system 42 for processing.

[0136] The magnetic I.D. tagging and detection system employs thefollowing components:

[0137] Particles 10:

[0138] Multiple different magnetic I.D.s are achieved by implantingindividual magnetic implants 14 of different sizes and magnetic fieldstrengths at different positions within the particle 10. Thus, a varietyof magnetic field strengths and orientations can be assigned toparticles having identical shape, size and density.

[0139] Sensors 40 a, 40 b and 40 c:

[0140] Sensors 40 a, 40 b and 40 c are positioned around the pipe 32containing the flowing product stream. The sensors 40 a, 40 b and 40 care arranged in sets of 3 equally sensitive sensors positionedequidistantly around the pipe perimeter.

[0141] The sensitivity of sensors 40 a, 40 b and 40 c is controlled bytwo methods (and their combinations):

[0142] 1. Varying lengths of soft iron (or other magnetically permeablematerial) magnetic flux concentrating material 52 extend within straps50 from sensor edges. The longer the length of the flux concentratingmaterial 52, the more sensitive the sensor 40 to the magnetic fieldpresence. The sensors 40 that need no sensitivity-enhancement are leftwithout flux concentrating material 52.

[0143] 2. Varying the driving voltage from batteries (or otherappropriate DC power sources) 44, 46 and 48 of each sensor group—sincethe output signal (voltage out) is dependent both on the input signal(voltage in) and the reduction of the sensor resistance caused by themagnetic field; the higher the input voltage, the higher the outputvoltage signal, i.e., more sensitive the sensor 40.

[0144] Both flux concentrator dimensions and the driving voltages ofindividual sensor clusters are adjusted so that clear detection anddifferentiation is achieved between the individual magnetically taggedparticle i.d.s. The exact dimensions of the flux concentrating material52 and the values of input voltages from batteries (or other appropriateDC power sources) 44, 46 and 48 are adjusted depending on the number andtype of tag i.d.s, but range from 3-10 inches and from 1.5 to 48 voltsrespectively. It is noted that the manufacturer of sensors 40,Nonvolatile Electronics, Incorporated (NVE), 11409 Valley View Road,Eden Prairie, Minn. 55344-3617, has established a recommended range ofabout 0.75 to about 24 volts as input voltages for GMR sensors 40. But,applicants were able to successfully use sensors 40 with voltagesranging from about 1.5 to about 48 volts.

[0145] Three levels of sensor sensitivity were implemented inapplicants' detector cluster design of FIG. 9 (the system may optionallyemploy more or less sensitivity levels or clusters), and werecolor-coded for illustration purposes:

[0146] The most sensitive sensors 40 c (coded red) were fitted with 6inch flux concentrators 52 and had input voltage of 36 volts frombattery 48. Thus, sensors 40 c were capable of detecting all insertedmagnetically tagged particles 10, including those with the weakestmagnetic implants 14.

[0147] The sensors 40 b with medium sensitivity (coded green) werefitted with 4 inch flux concentrators 52 and had input voltage of 24volts from battery 4G. Thus, sensors 40 b were capable of detecting allinserted magnetically tagged particles 10 with the exception of thosecontaining the weakest magnetic implants 14.

[0148] The least sensitive sensors 40 a (coded blue) were not fittedwith flux concentrators 52 and had input voltage of 12 volts frombattery 44. Thus, sensors 40 a were capable of detecting only thosemagnetically tagged particles 10 that were tagged with medium and largemagnetic implants 14 (0.1 gram and above).

[0149] Thus, in combination with the sequential insertion ofspecifically tagged particles 10, the i.d. system was established. Aparticle 10 tagged with the smallest magnetic implant 14 would bedetected only by the most sensitive (red) sensors 40 c; a particle 10tagged with the medium-sized magnetic implants 14 or multiple smallmagnetic implants 14 would be detected by sensors 40 c and 40 b (“red”and “green”) whereas particle 10 tagged with relatively large/strongmagnetic implants 14 or multiple small/medium magnetic implants 14 wouldbe detected by all (“red”, “green” and “blue”) sensors 40 c, 40 b and 40a. In all cases an additional identification mechanism is the magnitudeof the response of each sensor cluster.

[0150] The TESTPOINT™ software was customized to provide for a colorgraphical output from the data from the different sensors 40 a, 40 b and40 c. Thus, particular particles 10 were tracked according to thecolor-coding described above.

[0151] It is noted that the sensors 40 of the gasket configuration ofthe system of this invention as described in FIGS. 7 and 8 can becustomized to detect particular ranges of magnetic identifications in asimilar manner as just described.

[0152] Detection of Particle in a Package for Removal

[0153] Referring now to FIG. 10, a further alternative configuration forthe sensors of the method and system of this invention is depicted. Inthis configuration, the particle 10 including a magnetic implant isdetected in a package after the food stream is run through a continuousthermal processing line and packaged. The package 54 containing theparticle 10 is removed from the line.

[0154] Other packages that do not contain particles 10 then move alongthe line and, assuming residence time measurements and/or other thermaltreatment evaluations, such as microbial culturing from an inoculum packsuch as inoculum pack 18 described above, or data from a thermal memorycell such as thermal memory cell 20 described above, indicate sufficientlethality, can be sold to consumers. Thus, it is contemplated that themethod and system of this invention can be used in generating residencetime measurements, biovalidation calculations and other thermal historydata during the continuous thermal processing of a food product that isto be sold to consumers. Stated differently, it is contemplated that themethod and system of this invention can be implemented under normalprocessing run conditions to evaluate thermal treatment as a part of theregular quality control procedure for regular production runs, inaddition to facilitating fulfillment of requirements for a processfiling as required by the FDA.

[0155] Referring then to FIG. 10, packages 54 are moved along a conveyorbelt (not shown in FIG. 10). Straps 50 including GMR sensors 40 and fluxconcentrating material 52 are placed proximate to the conveyor belt.Batteries 34 are operatively connected to sensors 40. Outputs fromsensors 40 are directed to computer acquisition system 42. Maximumsensitivity sensors 40 are used in this embodiment.

[0156] Particle 10 in a single package 54 is detected, and anappropriate signal reaches computer 42. Computer 42 then provides asignal to a user as to which package 54 includes the particle 10 so thatit can be removed from the line.

[0157] Tables 3-6 below summarize preferred system dynamics, includinginjection dynamics. Tables 3-6 also set forth magnetic identificationdata for the particles in the food flow. TABLE 3 Insertion dynamicsBasic system 40 L/min flow rate 40 m hold tube (2 in. i.d.) Particles ataverage fluid velocity Other flow/length settings

[0158] TABLE 4 Insertion dynamics (basic) 40 L/min; 2 in; 40 m; avg.velocity Residence time 121.6 s For 400 particles: 13.5 hours; 32,429 LFor 3 replicate runs: 40.5 hours; 96,288 L

[0159] TABLE 5 Insertion dynamics: Programmed delay Max. part. velocity= 2 * avg. vel. (Residence time 60.8 s) Min. part. velocity = avg. vel.(residence time 121.6 s) Minimum delay 60.8 s For 400 particles:  6.76hours; 16,215 L For 3 replicate runs; 20.27 hours; 48,644 L

[0160] TABLE 6 Programmed delay + Magnetic I.D. I.D.s 400 particles 3runs 1. 6.76 hr; 16,215 L 20.27 hr; 48,644 L 2. 3.38 hr; 8,107 L 10.13hr; 24,322 L 3. 2.25 hr; 5,405 L  6.76 hr; 16,215 L 4. 1.69 hr; 4,053 L 5.07 hr; 12,161 L 5. 1.35 hr; 3,243 L  4.05 hr; 9,728 L

[0161]FIG. 12 is a graphical presentation of the hour and product amountdata information derived from a residence time profile generated from aconventional thermal process (upper bar graph and pie chart on the leftside of FIG. 12) as compared to the methods of this invention (lower bargraph and pie chart on the right side of FIG. 12). These graphs presentthe dramatic savings in time and product provided by the method andsystem of this invention.

[0162] The method and system of this invention provides for the use ofmagnetic tagging implants in combination with other sensing devicesimplanted in the particle (thermal memory cell, thermal pill, asdescribed in NASA Tech Briefs, June 1990, p. 106), microbial loadedmedia or real food products. It additionally provides for the concurrentresidence time measurement for the individual solid particle types formulti-phase products containing several different particle components(stews, vegetable mixes, soups, etc.).

[0163] Therefore, applicants' invention represents a significant advanceover all previously available or tested methods in that it ensuresreliable detection at all detection points and minimizes the time andproduct used through the application of calculated insertion delays andmultiple particle identification types. Additionally, the simulatedparticle density is adjusted to the experimentally determined targetdensity rather than an arbitrarily selected value such as initial orfinal particle density, initial carrier fluid density etc. Thisadjustment provides an improved level of safety against underprocessingin a variety of processing geometries and configurations. No specialinserts or viewing ports are necessary for detection and i.d.recognition. No special insertion device is needed—a first particle canbe simply inserted into a hopper and the timing delay for the remainingparticles can be started at the time of system entry detection.

[0164] It will be understood that various details of the invention maybe changed without departing from the scope of the invention.Furthermore, the foregoing description is for the purpose ofillustration only, and not for the purpose of limitation—the inventionbeing defined by the claims.

What is claimed is:
 1. A method of generating a residence timemeasurement of a particulate-containing food product while passing theproduct as a continuous stream through a thermal processing apparatus,the method comprising the steps of: (a) inserting at least onedetectable particle tagged with at least one magnetic implant into thestream at pre-selected intervals; (b) detecting the at least one implantusing at least one sensor located at a detection point downstream from alocation of the inserting of the at least one detectable particle, thesensor having a sensitivity such that the sensor is capable of detectinga magnetic field at least as low as 0.05 oersteds, wherein saiddetectable particle has a lower speed boundary limit of zero velocity;(c) determining a time of passage of the at least one detectableparticle in the stream using output from the at least one sensor; and(d) generating a residence time measurement for the stream using thetime of passage for the at least one detectable particle.
 2. The methodof claim 1, wherein the sensor has a sensitivity such that the sensor iscapable of detecting a magnetic field ranging from at least as low as0.05 oersteds to about 20 oersteds.
 3. The method of claim 1, furthercomprising providing a detectable particle wherein at least one physicalparameter of the particle that effects behavior of the particle in thestream is adjusted to provide a conservative residence time measurement.4. The method of claim 3, wherein the physical parameter is selectedfrom the group consisting of density, size, shape and combinationsthereof.
 5. The method of claim 4, wherein the density of the particleis adjusted to a pre-determined target density.
 6. The method of claim5, wherein the target density is that density with the highestlikelihood of including a fastest particle.
 7. The method of claim 1,wherein the magnetic implant comprises a material selected from thegroup consisting of neodymium iron boron, cobalt rare earth,aluminum-nickel, ceramic, organic, plastic-embedded metal or ceramic andcombinations thereof.
 8. The method of claim 1, wherein the pre-selectedintervals for inserting the detectable particles are selected tomaximize a number of inserted detectable particles per unit time and tominimize time and quantity of the stream used to generate the residencetime measurement.
 9. The method of claim 1, wherein the pre-selectedinterval comprises an amount of time that is less than an amount of timerequired to pass a first detectable particle through a predeterminedlength of the thermal processing apparatus.
 10. The method of claim 1,further comprising placing additional sensors at the detection point;and determining the time of passage in the stream for the at least onedetectable particle in the stream using output from each sensor.
 11. Themethod of claim 1, further comprising placing the at least one sensorproximate to the stream using a gasket.
 12. The method of claim 1,further comprising placing additional magnetic sensors at at least oneadditional detection point downstream from the location of the insertingof the detectable particles; and determining the time of passage in thestream for the at least one detectable particle in the stream usingoutput from each sensor.
 13. The method according to claim 12, furthercomprising placing additional magnetic sensors at a plurality ofadditional detection points downstream from the location of theinserting of the at least one detectable particle, and determining thetime of passage in the stream for the at least one detectable particlein the stream using output from each sensor.
 14. A method of generatinga residence time measurement of a particulate-containing food productwhile passing the product as a continuous stream through a thermalprocessing apparatus, the method comprising the steps of: (a) insertinga plurality of detectable particles, each particle tagged with at leastone detectable magnetic implant, into the stream at pre-selectedintervals; (b) detecting the at least one implant using at least onesensor located at a detection point downstream from a location of theinserting of the plurality of detectable particles, the sensor having asensitivity such that the sensor is capable of detecting a magneticfield of at least as low as 0.05 oersteds; (c) determining a time ofpassage in the stream for each of the plurality of detectable particlesin the stream using output from the at least one sensor; and (d)generating a residence time measurement for the stream using the time ofpassage for each of the plurality of detectable particles.
 15. Themethod of claim 14, wherein the sensor has a sensitivity such that thesensor is capable of detecting a magnetic field ranging from at least aslow as 0.05 oersteds to about 20 oersteds.
 16. The method of claim 14,wherein each particle in the plurality of particles has a differentmagnetic identification.
 17. The method of claim 16 wherein thedifferent magnetic identifications are provided by including within eachparticle a different magnetic implant.
 18. The method of claim 17,wherein the different magnetic implants vary according to a physicalparameter selected from the group consisting of number of implantswithin the particle, size of implant, shape of implant, mass of implant,magnetic material used, location of implant within the particle andcombinations thereof.
 19. The method of claim 14, wherein saiddetectable particles have a lower speed boundary limit of zero velocity.20. The method of claim 14, further comprising providing a plurality ofdetectable particles wherein at least one physical parameter of each ofthe plurality of particles that effects behavior of each of theparticles in the stream is adjusted to provide a conservative residencetime measurement.
 21. The method of claim 20, wherein the physicalparameter is selected from the group consisting of density, size, shapeand combinations thereof.
 22. The method of claim 21, wherein thedensity of the particle is adjusted to a pre-determined target density.23. The method of claim 22, wherein the target density is that densitywith the highest likelihood of including a fastest particle.
 24. Themethod of claim 14, wherein the magnetic implant comprises a materialselected from the group consisting of neodymium iron boron, cobalt rareearth, aluminum-nickel, ceramic, organic, plastic-embedded metal orceramic and combinations thereof.
 25. The method of claim 14, whereinthe pre-selected intervals for inserting the detectable particles areselected to maximize a number of inserted detectable particles per unittime and to minimize time and quantity of the stream used to generatethe residence time measurement.
 26. The method of claim 14, wherein thepre-selected interval comprises an amount of time that is less than anamount of time required for a first plurality of detectable particles topass through a predetermined length of said thermal processingapparatus.
 27. The method of claim 14, further comprising placing the atleast one sensor proximate to the stream within a gasket-type enclosure.28. The method according to claim 14, further comprising placingadditional sensors at the detection point; and determining the time ofpassage in the stream for the plurality of detectable particle in thestream using output from each sensor.
 29. The method according to claim14, further comprising placing additional magnetic sensors at at leastone additional detection point downstream from the location of theinserting of the detectable particles; and determining the time ofpassage in the stream for each of the plurality of detectable particlesin the stream using output from each magnetic sensor.
 30. The methodaccording to claim 29, further comprising placing the sensors proximateto the stream using a gasket.
 31. The method according to claim 29,further comprising placing additional magnetic sensors at a plurality ofadditional detection points downstream from the location of theinserting of the detectable particles; and determining the time ofpassage in the stream for each of the plurality of detectable particlesin the stream using output from each magnetic sensor.
 32. The methodaccording to claim 29, further comprising calibrating each of thesensors with a magnetic field of each of the detectable particles, suchthat each sensor detects a different range of particles.
 33. A methodfor conservatively evaluating thermal treatment in a continuous thermalprocess for a stream of a particulate-containing food product, themethod comprising the steps of: (a) inserting at least one detectableparticle tagged with at least one magnetic implant into the stream atpre-selected intervals, the detectable particle further comprising acargo component capable of providing thermal history data for theparticle, and wherein said at least one detectable particle possesses alower thermal conductivity than any particle in saidparticulate-containing food product; (b) detecting the at least oneimplant using at least one sensor located at a detection pointdownstream from a location of the inserting of the at least onedetectable particle, the sensor having a sensitivity such that thesensor is capable of detecting a magnetic field at least as low as 0.05oersteds, said detectable particle having a lower speed boundary limitof zero velocity; (c) obtaining said thermal history data from saidcargo component of said at least one detectable particle at saiddetection point; and (d) evaluating said thermal treatment for thestream using said thermal history data.
 34. The method of claim 33,wherein the cargo component is selected from the group consisting of athermal memory cell, a microbial load, and combinations thereof.
 35. Themethod of claim 33, wherein said food product is packaged for deliveryto a consumer after passing through said continuous thermal process, andsaid detection point comprises a point after the product is packaged.36. A system for generating a residence time measurement for aparticulate-containing food product while passing the product as acontinuous stream through a thermal processing apparatus, the systemcomprising: (a) at least one detectable particle tagged with at leastone detectable magnetic implant; (b) means for detecting the implant inthe particle, the means including at least one magnetic sensor, whereinthe sensor is capable of detecting a magnetic field of at least as lowas 0.05 oersteds; (c) means for determining a time of passage of the atleast one detectable particle in the stream using output from the atleast one sensor; and (d) means for generating a residence timemeasurement for the stream using the time of passage for the at leastone detectable particle.
 37. The system of claim 36, further comprisinga plurality of detectable particles, each tagged with at least onedetectable magnetic implant.
 38. The system of claim 37, wherein eachparticle in the plurality of particles has a different magneticidentification.
 39. The system of claim 38, wherein the differentmagnetic identifications are provided by including within each particlea different magnetic implant.
 40. The system of claim 36, wherein thedifferent magnetic implants vary according to a physical parameterselected from the group consisting of number of implants within theparticle, size of implant, shape of implant, mass of implant, magneticmaterial used, location of implant within the particle and combinationsthereof.
 41. The system of claim 36, wherein the sensor has asensitivity such that the sensor is capable of detecting a magneticfield ranging from at least as low as 0.05 oersteds to about 20oersteds.
 42. The system of claim 36, wherein at least one physicalparameter of the at least one particle that affects behavior of the atleast one particle in the stream is adjusted to provide a conservativeresidence time measurement.
 43. The system of claim 42, wherein thephysical parameter is selected from the group consisting of density,size, shape and combinations thereof.
 44. The system of claim 43,wherein the density of the particle is adjusted to a pre-determinedtarget density.
 45. The system of claim 44, wherein the target densityis that density with the highest likelihood of including a fastestparticle.
 46. The system of claim 36, wherein the magnetic implantcomprises a material selected from the group consisting of neodymiumiron boron, cobalt rare earth, aluminum-nickel, ceramic, organic,plastic-embedded metal or ceramic and combinations thereof.
 47. Thesystem of claim 36, further comprising a means for inserting thedetectable particles into the stream, the means for inserting thedetectable particles calibrated such that the detectable particles areinserted according to insertion delay intervals that are selected tomaximize a number of inserted detectable particles per unit time and tominimize time and quantity of the stream used to generate the residencetime measurement.
 48. The system of claim 36, wherein the means fordetecting the magnetic implant further comprises a gasket, the at leastone sensor mounted within the gasket.
 49. The system of claim 36,wherein the means for detecting the implant further comprises aplurality of sensors.
 50. The system of claim 49, wherein the means fordetecting the magnetic implant further comprises a gasket, the sensorsmounted within the gasket.
 51. The system of claim 49, wherein each ofthe sensors is calibrated according to a magnetic field of each of thedetectable particles, such that each sensor detects a different range ofparticles.
 52. The system of claim 36, further comprising an additionalmeans for detecting the implant locatable at at least one additionaldetection point downstream from the location of the inserting of thedetectable particles.
 53. The system of claim 52, further comprisingadditional means for detecting the implant locatable at a plurality ofadditional detection points downstream from the location of theinserting of the detectable particles.
 54. The system of claim 36,further comprising means for displaying output from said at least onesensor graphically.
 55. A system for generating a residence timemeasurement for a particulate-containing food product while passing theproduct as a continuous stream through a thermal processing apparatus,the system comprising: (a) at least one detectable particle tagged withat least one detectable magnetic implant; (b) means for detecting theimplant in the particle, the means comprising a gasket and at least onemagnetic sensor mounted within the gasket; (c) means for determining atime of passage of the at least one detectable particle in the streamusing output from the at least one sensor; and (d) means for generatinga residence time measurement for the stream using the time of passagefor each of the detectable particles.
 56. The system of claim 55,wherein the means for detecting the implant further comprises aplurality of sensors mounted within the gasket.
 57. The system of claim55, further comprising a plurality of detectable particles, eachparticle including at least one magnetic implant.
 58. The system ofclaim 57, wherein the means for detecting the implant further comprisesa plurality of sensors mounted within the gasket.
 59. The system ofclaim 58, wherein each of the sensors is calibrated according to amagnetic field of each of the detectable particles, such that eachsensor detects a different range of particles.
 60. A sensor assembly foruse in measuring residence time for a particulate-containing foodproduct while passing the product as a continuous stream through athermal processing apparatus, the sensor assembly comprising a gasketand at least one magnetic sensor mounted within the gasket.
 61. Thesensor assembly of claim 60, further comprising a plurality of sensorsmounted within the gasket.
 62. In combination, (1) a detectable particlefor use in evaluating thermal treatment for a particulate-containingfood product while passing the product as a continuous stream through athermal processing apparatus, the detectable particle comprising adetectable magnetic implant and a carrier, and (2) a sensor having asensitivity such that the sensor is capable of detecting a magneticfield at least as low as 0.05 oersteds.
 63. The combination of claim 62,wherein the particle further comprises at least one additional magneticimplant.
 64. The combination of claim 63, wherein the at least oneadditional magnetic implant differs from the other magnetic implantaccording to a physical parameter selected from the group consisting ofsize, shape, mass, magnetic material used, location within the particleand combinations thereof.
 65. The combination of claim 62, wherein thesensor has a sensitivity such that the sensor is capable of detecting amagnetic field ranging from at least as little as 0.05 oersteds to about20 oersteds.
 66. The combination of claim 62, wherein at least onephysical parameter of the particle that affects behavior of the particlein the stream is adjusted to provide a conservative residence timemeasurement.
 67. The combination of claim 66, wherein the physicalparameter is selected from the group consisting of density, size, shapeand combinations thereof.
 68. The method of claim 67, wherein thedensity of the particle is adjusted to a pre-determined target density.69. The method of claim 68, wherein the target density is that densitywith the highest likelihood of including a fastest particle.
 70. Thecombination of claim 62, wherein the magnetic implant comprises amaterial selected from the group consisting of neodymium iron boron,cobalt rare earth, aluminum-nickel, ceramic, organic, plastic-embeddedmetal or ceramic and combinations thereof.
 71. The combination of claim62, wherein the carrier comprises material selected from the groupconsisting of polystyrene, copolymers thereof, polypropylene, copolymersthereof, and combinations of polystyrene, copolymers thereof,polypropylene and copolymers thereof.
 72. The combination of claim 62,wherein the carrier comprises a container.
 73. The combination of claim72, wherein the container further comprises a lid, a body and a gasket,the gasket cooperating with the lid and the body to form a seal betweenthe lid and the body.
 74. The combination of claim 62, wherein themagnetic insert has a configuration selected from the group consistingof a circle, a sphere, a tetrahedron, an asterisk, a cross, a cube, atriangle, a pyramid, a square, a rectangle, a needle, a coil, andcombinations thereof.
 75. The combination of claim 62, wherein thecarrier comprises an actual food particle.
 76. The combination of claim62, further comprising a cargo component.
 77. The combination of claim76, wherein the cargo component is selected from the group consisting ofan inert material, a thermal memory cell, a microbial load, an actualfood particle, a thermal pill, thermal insulating material, atransponder and combinations thereof.